X-ray imaging is a useful tool to identify unknown objects. It is often used for the detection of explosives and contraband in situations where it is impractical or unsafe to move the object being imaged. Simple transmission imaging and backscattering imaging methods have been utilized for such “field” applications. Additionally, CT scanners have been installed in fixed locations, such as airports, for enhanced security screening.
Modern CT scanners typically use an x-ray tube and a digital detector mounted on a gantry. The x-ray tube and digital detector move around the gantry to collect a series of images which are used for image reconstruction
Once the images are acquired, image reconstruction requires knowledge of precise locations of an x-ray source and an x-ray detector with respect to the object being imaged for each projection view taken.
Stationary CT and tomosynthesis scanners are also known. These scanners are referred to as “stationary” because of the use of an array of x-ray sources spatially distributed in a fixed pattern. The individual projection images are taken by activating the individual x-ray sources without moving the x-ray source or the detector.
While the process works reasonably well for systems installed in dedicated spaces, it becomes cumbersome and often impractical for mobile and field operations. The heavy mechanical gantry needed for mechanical stability takes up space and makes it difficult to design mobile tomography scanners that can be useful in situations where the patient cannot be easily transferred. Additionally, a fixed trajectory limits the imaging to simple acquisition geometry such as linear or circular arc acquisition due to practical engineering constraints, which may not provide the most efficient projection image set for every object and application.
Where x-ray imaging is being utilized for explosive detection in the field (e.g., in a public location), it is necessary for the imaging equipment to be placed adjacent to the object being imaged, but for the operator to be positioned remotely in order to ensure the safety of the operator in case of detonation. In such instances, the images can be transmitted through any of a number of wireless communication protocols.
A prior art portable x-ray imaging system is shown in FIG. 1, which includes, for example, a battery-powered x-ray source, generally designated 10, a flat panel x-ray detector, generally designated 20, and a wireless transmission device, generally designated 30. In such systems, the operator must place the x-ray detector and the x-ray source adjacent to the object, exposing the operator to potential danger from an explosion during placement of these system components. Some portable x-ray imaging systems attempt to address this by placing the x-ray source and the detector on an unmanned rover, generally designated 50, such as is shown in FIG. 2, that is then remotely driven to the object of interest to generate the x-ray images. As such, the currently known portable x-ray imaging systems are either carried by an operator or positioned by a ground vehicle.
At present, there exists a need for a convenient way to remotely obtain CT images of an object away from a fixed installation site (e.g., an airport). CT technology provides valuable three-dimensional (“3D”) images of the internal structure of an object, removing overlapping, and providing better diagnosis compared to conventional two-dimensional (“2D”) x-ray image. Dual energy CT data also enables chemical identification for determination of the presence of explosives, and can even differentiate between types of explosives. Dual energy CT is currently used in airports for inspection of checked baggage. As such, a remote-controlled CT scanner capable of generating a 3D image of an object without being physically transported to the object by the operator is highly desirable.